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Our brains can map the physical barriers of a room in just 100 milliseconds

A team of neuroscientists has identified the region of the human brain that is dedicated to perceiving the barriers which define the traversable space around us, such as walls or ceilings, so that we can navigate safely through our environment.

This brain region processes our spatial constraints at incredibly fast speeds and likely contributes to our instant sense of new surroundings. The research is shedding new light on the complex computations performed by our brains to help us get around.

Study senior author Dr. Nikolaus Kriegeskorte is a principal investigator at Columbia University’s Mortimer B. Zuckerman Mind Brain Behavior Institute.

“Vision gives us an almost instant sense where we are in space, and in particular of the geometry of the surfaces – the ground, the walls – which constrain our movement. It feels effortless, but it requires the coordinated activity of multiple brain regions,” said Dr. Kriegeskorte. “How neurons work together to give us this sense of our surroundings has remained mysterious. With this study, we are a step closer to solving that puzzle.”

Using two cutting-edge brain-imaging technologies, the researchers examined the mental responses of volunteers as they were shown images of various three-dimensional scenes. The image may depict a typical room with three walls, a ceiling, and a floor, but then was abruptly changed by the removal of a wall or a ceiling.

“By doing this repeatedly for each participant as we methodically altered the images, we could piece together how their brains encoded each scene,” said study first author Dr. Linda Henriksson.

The occipital place area (OPA), an intermediate-level stage of cortical processing, stood out in the brain scans of the participants.

“Previous studies had shown that OPA neurons encode scenes, rather than isolated objects,” said Dr. Kriegeskorte. “But we did not yet understand what aspect of the scenes this region’s millions of neurons encoded.”

After analyzing the brain scans, the team discovered that the OPA activity represented the geometry of the scenes. The OPA activity patterns reflected the presence or absence of each component, such as a ceiling or a wall, and projected a detailed picture of the overall configuration.

The brain region seemed to ignore the surface appearance of the various components in order to focus solely on the geometric patterns. The OPA managed to get a sense of a room’s layout in just 100 milliseconds.

“The speed with which our brains sense the basic geometry of our surroundings is an indication of the importance of having this information quickly,” said Dr. Henriksson. “It is key to knowing whether you’re inside or outside, or what might be your options for navigation.”

In the future, the research team plans to incorporate virtual reality technology to create more realistic 3D environments for participants to experience.

“We would like to put these things together and build computer vision systems that are more like our own brains, systems that have specialized machinery like what we observe here in the human brain for rapidly sensing the geometry of the environment,” said Dr. Kriegeskorte.

The study is published in the journal Neuron.

By Chrissy Sexton, Staff Writer

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